Pipe couplings using circumferential bands are commonly employed in connecting aligned end-to-end pipes as shown in U.S. Pat. No. 4,473,246. However, such couplings do not provide high resistance to significant tension forces in the pipes, and it is known to resist high tension forces with this type of coupling by using outrigger clamps in conjunction with a central clamp as shown in U.S. Pat. No. 4,502,189. Such clamps comprise a generally circular band portion terminating in opposed connecting end flanges, and the outrigger clamps are attached to the central clamp by strap elements. Fasteners in the form of a nut and bolt are passed through the opposed connecting flanges and are tightened to draw the connecting flanges toward each other.
Although the aforementioned pipe couplings have proven to be dependable they have a relatively complicated and expensive construction or require a relatively large number of parts which makes for a time consuming assembly process and adds to the overall cost of the product. Also, the outrigger type clamp requires a specific configuration and cannot be modified to a non-outrigger type if the extra resistance to tension forces is not required.
An object of the invention is to provide an axial force resisting pipe coupling having outrigger clamps wherein the pipe coupling requires a small number of components, is of a simple construction, economical to manufacture, and simple and efficient to use.
A further object of the invention is to provide an axial force resisting pipe coupling having a central clamp and a pair of outrigger clamps wherein the outrigger clamps can be retrofitted to a conventional circumferential clamp and the invention permits a variety of clamp configurations to be assembled from a minimum number of inventoried parts.
Another object of the invention is to provide an axial force resisting pipe coupling having outrigger clamps wherein the outrigger clamps are provided with projections for embedding into the pipe members to increase the axial force resistance of the coupling.
An axial force resisting pipe coupling in accord with the invention consist of a central clamp and two axially spaced outrigger clamps. Each of the clamps are attached to a common outrigger bar and are fabricated by forming a piece of sheet metal into a generally circular configuration defining a circular band portion terminating in opposed connecting end flanges directed radially outwardly from the band. The flanges are rolled back defining loops which receive reinforcing bars and are provided with apertures which align with apertures defined in the outrigger bar. Each of the aligned apertures receive a carriage bolt on which a nut is threaded to mount the clamps to the outrigger bar and the same nut and bolt also facilitate circumferential contraction and expansion of the clamps.
In a typical application the central clamp overlaps the aligned ends of the pipe members to be joined while each of the outrigger clamps circumscribes one of the pipe members at an axially spaced distance from the central clamp. Tightening of the nuts and bolts is effective to draw the opposed flanges toward each other and thereby impart circumferential tension to the clamps sufficient to maintain the pipes together. If desired, the outrigger clamps may be fashioned with projections or dimples for embedding into the pipes to increase the friction of the outrigger clamps and minimize the likelihood of the pipes separating due to high tension forces.
If a leak resistant joint is specified, sleeve elements may be disposed within the central clamp to impart a leak resistant characteristic to the joint. These sleeve elements may include a metal sleeve disposed within the central clamp, and an elastomeric sleeve disposed within the metal sleeve. Each of the sleeves overlap the ends of the pipes and are tightened to the pipes simultaneously with the drawing together of the opposed flanges. The metal sleeve tightens the elastomeric sleeve to the pipe ends which provides leak resistance for the joint.
As the bar connecting the outrigger clamps to the central clamp is attached to the central clamp by its constricting fasteners, and the bar is likewise attached to the outrigger clamps, the bar and outrigger clamps may be easily retrofitted to existing central clamps and the practice of the invention minimizes inventories and provides a versatility of clamp availability not previously available.
The fact that the outrigger clamps and central clamps are attached to a common bar by fastening means which are also utilized to facilitate circumferential contraction and expansion of the clamps provides a coupling of a simple, economical construction which is readily assembled, convenient to install and capable of resisting high tension forces.